Lesson 12 — Intermediate

Computer Security Basics

Jitna computer connected hua, utni threats badhi. Is lesson mein hum dekhenge cyber threats ke type (virus, malware, hacking) aur unse bachne ke tarike — ye aaj har computer user ke liye zaroori hai.

⏱ 14 min• Intermediate• Internet & Web

Computer security kya hai

WHAT

Computer security (cybersecurity) ka matlab hai system, data aur network ko unauthorized access, damage aur attacks se protect karna. CIA triad — Confidentiality, Integrity, Availability — ka goal.

WHEN

Jab bhi internet use ho, file share ho, ya unknown link open ho — risk hai. Har user ko security ka dhyan rakhna chahiye.

WHERE

Antivirus, firewall, passwords, encryption — har jagah security layers hoti hain. Banking app sabse zyada secure hota hai.

Security ka goal: Confidentiality (sirf sahi insaan dekhe), Integrity (data badla na ho), Availability (jab chahiye tab mile). In teeno ka balance = secure system.

Threats aur attacks ke type

Malware (harmful software):
  Virus     : khud ko copy karta hai, host file se attached
  Worm      : network se khud spread (host file nahi chahiye)
  Trojan    : useful dikh kar andar aata hai (game/app)
  Ransomware: data encrypt karke ransom mangta hai
  Spyware   : chupke se tumhari activity record karta hai
  Adware    : annoying ads dikhata hai

Attacks:
  Phishing : fake email/site se credentials churaana
  DoS/DDoS : server ko overload karke down karna
  MITM     : beech mein aakar data churaana (public Wi-Fi)
  SQLi     : database query inject karke data leak

Common confusion: Virus ko host chahiye (file attach), worm ko nahi (khud network pe spread). Trojan dikhne mein useful hai par andar kharab — ye teeno ka farak exam mein aata hai.

Protection ke tarike

Antivirus + updates: definitions update rakho, regular scan.
Firewall: incoming/outgoing traffic filter karta hai.
Strong passwords + MFA: long, unique + 2nd factor (OTP).
Encryption: data ko code bana do (AES, RSA) — chori ho bhi toh padhna mushkil.
Backups: 3-2-1 rule — 3 copies, 2 media, 1 offsite.
Cautious clicks: unknown links/attachments mat kholo.

Encryption do type ki hoti hai — Symmetric (ek key encrypt+decrypt, fast) aur Asymmetric (public+private key, safe). HTTPS dono use karta hai.

Ethical hacking vs cracking

White Hat (Ethical) : permission lekar vulnerabilities dhhoondhta hai, fix karwata hai — legal
Black Hat (Cracker) : unauthorized access, data churaana, damage — illegal
Grey Hat           : bina permission dhhoondhta hai but intent behtar (still risky)

Cyber laws : IT Act (India) — unauthorized access +3 years imprisonment

Ethical hacking = security ka achha insaan. Companies white hats ko hire karti hain taaki vulnerabilities pehle fix ho jaayein black hat se pehle.

Exercise

Question: CIA triad ke teeno components comma se likho.

Question: Data ko encrypt karke ransom mangne wale malware ka naam kya hai?

Question: Fake email se credentials churaana kya kehlata hai? (phishing / dos / mitm)

Common mistakes

Virus aur worm ka farak ulta bolna: Virus = host file chahiye, worm = khud network se spread. Ye classic exam question hai.
Firewall aur antivirus ko same samajhna: Firewall traffic filter karta hai (network), antivirus malware scan karta hai (files). Dono alag layer hain.
Encryption ka matlab secure samajhna: Encryption data ko unreadable banata hai — par key leak ho gayi toh safe nahi. Key management important hai.

Desi example: UPI fraud se bachna

Aaj sabse zyada fraud UPI/phone pe hota hai. Simple rules se 90% bach sakta hai:

Kabhi OTP/PIN kisi ko mat batao
Unknown link click mat karo (phishing)
Public Wi-Fi pe banking mat karo
Screen share app se door raho

Exam mapping (TCS / CUET)

TCS NQT: malware types (virus vs worm vs trojan).
CUET: CIA triad + encryption basics.
Trap: "Trojan spreads like worm" — galat, wo khud spread nahi, user install karta hai.

Lesson complete?

Security basics clear. Agla lesson — Cloud Computing — mein dekhenge cloud kya hai aur kyun useful hai.